Our mission, should we choose to accept it…

14102009

I’ve decided to take the time in Christchurch and the flight to McMurdo to explain a little more about ENDURANCE and it’s mission.

The ENDURANCE robot

ENDURANCE (the Environmentally Non-Disturbing Under-ice Robotic ANtarctiC Explorer) is a robotic submersible vehicle for scientific exploration. It is being deployed at Lake Bonney to allow us to explore a very unique and extreme environment which no person has ever seen before. Lake Bonney sits in the Dry Valleys region of Antarctica, which is one of the few areas on the continent not completely covered by ice. It is the coldest, driest land area on Earth, and is about as close to a Martian environment as you can get without leaving this planet. Very few things are able to live in this environment, but those that can may give us important clues about how and where life on Mars, if there is any, could survive. This fragile environment is also very sensitive to climate change, and monitoring changes here can provide a sort of advanced warning of how the climate is changing.

The lake is a very unique environment. The Dry Valleys used to be fjords, in other words, they used to be filled with sea water. The bottom layers of Lake Bonney are formed out of the evaporated remnants of this old sea water which has been carbon-dated to an age of 20,000 years. This ancient, extremely salty (up to 5 times sea water) water fills the lake to a depth of about 22 m. On top of that floats a layer of fresh water about 12 m thick, which is accumulated from the yearly melt coming from the surrounding glaciers. The whole lake is covered with a 3-4-m-thick permanent layer of ice, which keeps the interaction between the lake and the surrounding environment to a minimum.

West Lake Bonney with the Taylor Glacier and Blood Falls

The west end of Lake Bonney is formed by the massive glacial wall of the Taylor Glacier. A strange geological feature is present on the side of the glacier next to the lake. Blood Falls, named for the red coloring created by the high concentrations of iron in the water, emerges from the side of the glacier and harbors several totally unique species of microbial life. It is seen as a good analog to where life might be found on other planets. It is theorized that the water which flows very irregularly from the falls comes from another reservoir of ancient sea water which is now completely covered by the glacier and from time to time gets squirted out as the glacier moves. It’s highly likely that there are other outlets for this water underneath the glacier, and they may be environments for additional types of life. This is one thing ENDURANCE is being sent to find out.

ENDURANACE is capable of navigating on its own underwater following some programmed behaviors, and carries all its own power in a two big battery banks. To keep an eye over its shoulder and be able to send commands in case ENDURANCE encounters problems it doesn’t yet know how to deal with, we have connected a floating fiber-optic line to it to send and receive information at a central control station. It will explore the lake with sonar sensors to map out the geometry of the lake floor and the glacier and with a suite of chemical, light and biological sensors to examine the properties of the water. To avoid disturbing the pristine, ancient waters, ENDURANCE can only operate in the upper, freshwater layer of the lake. In order to be able to get measurements through the entire depth of the lake water, the biochemical sensors are all incorporated into a package (we call it the sonde), which is spooled out on a winch system at points on a regular grid throughout the lake.

This year, we are planning some exciting additional maneuvers. When ENDURANCE was scanning the glacier face last year, it revealed what appeared to be a large floating portion of the glacier. While the scientists had expected the glacier to extend all the way to the bottom of the lake, the wall stopped at about 15 meters depth, with open water underneath for as far as ENDURANCE’s sonar sensors could see. But since the top of the void was below the freshwater layer where ENDURANCE could maneuver, we couldn’t get a good view angle into the cave and see all the way to the back. Since the really interesting water chemistry and interactions seem to be coming from the glacier and what potentially lies beneath it, the scientists really want to be able to see the entire portion of the glacier that’s in contact with the lake. This is one of the most important scientific objectives of the campaign. In other words, Taylor Glacier or bust, baby!

So, this year, we hope to be able to carefully take ENDURANCE next to the glacier and down into the saltwater layer to get a good view of what’s going on under there. If things look safe and there’s enough room, we may even try to have ENDURANCE carefully maneuver under the glacier to get some chemical readings using the sonde. Since salt water makes things more buoyant, this will mean ENDURANCE will have to carry more ballast weight than it does in the fresh water. A lot more weight. Given the high salinity of the lower layers and the size of ENDURANCE, we estimate it will be something like 250 kg of lead. In fact, with this amount of ballast, ENDURANCE won’t be able to power itself up through the freshwater layer again. So we’ll have to rig up a system to remove the weights while ENDURANCE is down in the saltwater layer to allow it to come back home.

In addition to getting right up under Taylor Glacier, ENDURANCE will also be repeating the program from last year and finishing up those parts we didn’t get to: chemically sampling the entire lake on a 100-m grid, mapping out the geometry of the lake bottom, and photographing and sonar mapping the entire glacier face.

Sucessfully sampled locations for the 2008 Lake Bonney campaign.

The Stone Aerospace page on ENDURANCE also has a slightly more thorough technical explanation of the robot.

The ballast would stay on the ‘bot the whole time, we still have to develop the exact procedure to pull the ‘bot up with the ballast through the fresh water to recover. Either we’ll have a strong line permanently attached to ENDURANCE when it goes under the glacier, or we may have a diver go just down the hole and clip on a line when ENDURANCE is ready to be retrieved.

Hey!
Amazing research! I can’t imagine how it must feel to be a part of something like this. I bet you guys get to be really close as a team. I bet the breakup at the end is slightly emotionally distressing. Anyway, fantastic operation. Do you know of any blogs or updates that anyone on the team will be doing (besides Vickie’s on the Stone Aerospace website) and where I might find them?